Moving-magnet type linear d.c. brushless motor having plural moving elements

• US 5,023,495 A
• Filed: 04/17/1990
• Issued: 06/11/1991
• Est. Priority Date: 04/17/1990
• Status: Expired due to Fees

• Current Assignee: Hitachi America Limited (Hitachi, Ltd.), Shicoh Engineering Company Limited Kanagawa
• Original Assignee: Hitachi Metals & Shicoh Engine
• Inventors: Miyao, Osami, Ohsaka, Masayuki
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US07/509,760
• Time in Patent Office: 420 Days
• Field of Search: 310/12, 310/13, 310/14, 310/15, 318/135, 318/37, 318/38, 318/115
• US Class Current: 310/12.15
• CPC Class Codes: H02K 41/031 of the permanent magnet type
• CPC Class Codes: H02P 6/006 Controlling linear motors

Abstract

A moving-magnet type linear d.c. brushless motor having plural moving elements on a traveling track, and including a stator armature on the traveling track; n moving elements, each including a thrust-generating field magnet having P contiguous magnetic poles of alternating N and S polarity, where n is an integer greater than 1 and P is an integer of at least 1, the moving elements having one side facing the stator armature and traveling separately and independently along the traveling track; a plurality of position-detecting magnets, each corresponding to a different one of the moving elements and having P magnetic poles of N and S polarity at in-phase positions of substantially the same pitch relative to the poles of the thrust-generating magnets; and position detecting means including a group of position sensors corresponding to each position-detecting magnet for generating an electric current in the stator armature to move the moving elements in predetermined directions separately and independently, each position sensor detecting the magnet poles of only the corresponding position-detecting magnet.

Claims

1. A moving-magnet type linear d.c. brushless motor having plural moving elements, which comprises:

a stator armature provided along a traveling track of moving elements;

n moving elements, each including a thrust-generating field magnet having an arrangement of P contiguous magnetic poles of alternating N and S polarity, where n is an integer of at least 2 and P is an integer of at least 1, the moving elements being face to face with the stator armature and traveling separately and independently;

n position-detecting magnets, which are provided respectively on said n moving elements each of the position-detecting magnets having P magnetic poles of N and S polarity at in-phase position relative to the thrust-generating field magnets and substantially the same pitch as that between N and S magnetic poles in each of the thrust-generating field magnets; and

n groups of position sensors, each group facing a corresponding one of the position-detecting magnets, and detecting signals from the magnetic poles of the corresponding position-detecting magnet, so that in accordance with respective detected signals of positions of the poles of the position-detecting magnets from said respective group of the position sensors, an electric current is caused to flow into the stator armature facing the thrust-generating field magnet of said moving element having said position-detecting magnet so as to generate thrust, which causes said detected moving element to move in a predetermined direction, whereby said moving elements are energized and controlled to travel separately and independently.

2. The moving-magnet type linear d.c. brushless motor as claimed in claim 1, wherein the thrust-generating field magnets are also used as said position-detecting magnets without separately providing any position-detecting magnets.

6. The moving-magnet type linear d.c. brushless motor as claimed in claim 1, wherein each of said n position-detecting magnets is provided at a position on its corresponding moving element in such a manner that the traveling tracks according to traveling of the moving elements are in positions different from one another, and said n groups of position sensors are separately provided at positions different from one another on the side of the stator armature so as to face said n position-detecting magnets respectively, so that each of the position sensor groups detects only its corresponding position-detecting magnet.

7. The moving-magnet type linear d.c. brushless motor as claimed in claim 6, wherein each of said n position-detecting magnets is positioned on its corresponding moving element in such a manner that the traveling tracks according to traveling of the moving elements are in positions different from one another, and said n groups of position sensors are separately provided at positions different from one another on the side of the stator armature facing said n position-detecting magnets respectively, each of the groups of position sensors being magnetically isolated from the position-detecting magnets other than the corresponding position-detecting magnet, so that each group of the position sensors detects only its corresponding position-detecting magnet.

8. The moving-magnet type linear d.c. brushless motor as claimed in claim 7, wherein at least one of said n position-detecting magnets comprises a thrust-generating field magnet.

3. A moving-magnet type linear d.c. brushless motor having plural moving elements, said motor comprising:

a stator armature provided along a traveling track of moving elements, the armature having opposite sides;

first and second moving elements having respective first and second thrust-generating field magnet-cum-position-detecting magnets with contiguous poles of alternating N and S polarity face to face with the stator armature, said elements being movable separately and independently;

a first group of position sensors provided on one side of the stator armature so as to detect only the N or S magnetic pole of the first thrust-generating field magnet-cum-position-detecting magnet in the first moving element, so that when the first group of the position sensors detects an N or S pole of the first thrust-generating field magnet-cum-position-detecting magnet in the first moving element, an electric current is caused to feed to the stator armature facing the field magnet in the first moving element so as to generate thrust by which the first moving element is caused to travel in a predetermined direction; and

a second group of position sensors provided on the other side of the stator armature so as to detect only the N or S magnetic pole of the second thrust-generating field magnet-cum-position-detecting magnet in the second moving element, so that when the second group of the position sensors detects an N or S pole of the second thrust-generating field magnet-cum-position-detecting magnet in the second moving element, an electric current is caused to feed to the stator armature facing the field magnet in the second moving element so as to generate thrust by which the second moving element is caused to travel in a predetermined direction.

4. The moving-magnet type linear d.c. brushless motor as claimed in claim 3, wherein the first thrust-generating field magnet-cum-position-detecting magnet provided on the first moving element is arranged on the first moving element with it shifted in the direction of one side of the stator armature and the second thrust-generating field magnet-cum-position-detecting magnet provided on the second moving element is arranged on the second moving element with it shifted in the direction of the other side of the stator armature.

5. A moving-magnet type linear d.c. brushless motor having plural moving elements, said motor comprising:

a stator armature provided along a traveling track of moving elements;

first and second moving elements having respective first and second thrust-generating field magnets with contiguous poles of alternating N and S polarity face to face with the stator armature, said elements being movable separately and independently;

said respective thrust-generating field magnets being located on the same traveling track without shifting their positions from each other in directions perpendicular to the traveling direction of the moving elements, the first moving element emitting leakage magnetic flux from one side of its thrust-generating field magnet, but not emitting leakage magnetic flux from the other side thereof, the second moving element not emitting leakage magnetic flux from one side of its thrust-generating field magnet, but emitting leakage magnetic flux from the other side thereof, a first group of position sensors provided on one side of the stator armature so as to detect only the leakage magnetic flux of N or S polarity, which is emitted from the thrust-generating field magnet in the first moving element, so that when the first group of the position sensors detects the leakage magnetic flux of an N or S pole, which is emitted from the thrust-generating field magnet in the first moving element, an electric current is caused to feed to the stator armature facing the thrust-generating field magnet in the first moving element so as to generate thrust by which the first moving element is caused to travel in a predetermined direction, and a second group of position sensors provided on the other side of the stator armature so as to detect only the magnetic flux of N or S polarity, which is emitted from the other side of the thrust-generating field magnet in the second moving element, so that when the second group of the position sensors detects the leakage magnetic flux of an N or S pole, which is emitted from the thrust-generating field magnet in the second moving element, an electric current is fed to the stator armature facing the thrust-generating field magnet in the second moving element so as to generate thrust by which the second moving element is caused to travel in a predetermined direction.

9. A moving-magnet type linear d.c. brushless motor having plural moving elements on a traveling track, comprising:

a stator armature on the traveling track;

n moving elements, each including a thrust-generating field magnet having P contiguous magnetic poles of alternating N and S polarity, where n is an integer greater than 1 and P is an integer of at least 1, the moving elements having one side facing the stator armature and traveling separately and independently along the traveling track;

a plurality of position-detecting magnets, each corresponding to a different one of the moving elements and having P magnetic poles of N and S polarity at in-phase positions of substantially the same pitch relative to the poles of the thrust-generating magnets; and

position detecting means including a group of position sensors corresponding to each position-detecting magnet for generating an electric current in the stator armature to move the moving elements in predetermined directions separately and independently, each position sensor detecting the magnet poles of only the correspondingly position-detecting magnet.